Alternating-current electromagnet



March 25, 1930. H. N. PACKARD 1,752,023

ALTERNATING CURRENT ELECTROMAGNET Filed Feb. ll, 1924 i. Ill

A TTORAE Y Patented Mar. 25, 1930 UNITEDv STATES PATENT OFFICE HORACE N.PACKRD, 0F A'WAT.`J"TATOSA, WISCONSIN, .ASSIGIN'OR, BY MESNE .ASSIGN-MENTS, TO THE CUTLER-HAMMER, INC., A. CORPORATION OF DELAWAREAiTERNATING-CURRENT ELECTROMAGNET Application led February 11, 1924.Serial No. 691,897.

This invention 'relates to alternatingA current electromagnets and moreparticularly to shading coils therefor.

Alternating current electromagnets are usually provided with a shadingcoil to prevent humming or chattering of the magnet armature and it iscommon practice to employ a shading coil consisting of a single piece ofwire formed'to provide a loop and l having its ends secured together bywelding.

Such shading coils very often break, especially at or adjacent the weld,after a relatively' small number of operations of the magnet, and it hasbeen found that such breakage .is largely due to the fact that the coilis relatively rigid and incapable of withstanding shocks caused byimpact of thearmature member against the field member.

The present invention has among its pb- 2o jects to provide an improvedshading coil which will overcome the aforesaid objection. Various otherobjects and advantages of the invention will hereinafter appear.

The accompanying drawing illustrates an y' 25 embodimentl of theinvention which will now' be described, it, being understood 4that theembodiment illustrated can be Vmodied `in A certain respects withoutdeparting from th scope'oftheappended claims.

In the drawing, I Figure 1 is a side elevational view of anelectromagnet embodying the invention, the Y operating winding:v of themagnet being shown in section;

Fig. 2 is a front elevational view of the field member shown in Fig. 1,and

Fig. 3 is a detail view ofthe shading c oil shown in Figs. 1 andA 2.

Referring to Fig. 1 the same lillustrates an electromagnet including analternating cur-y rent windings 1 carried by eld member 2 and anarmature member 3 pivotally mounted on a pin 4 carried by said fieldmember. The field member 2 includes a U-Shaped laminated core member 5fixed to a rigid sup- )orting member 6 while the armature memer is madeup of a plurality of laminations 7 fixed to a rigid supporting arm 8.Arm 8.

is provided with spaced bearing portions 9 for receiving pin ,4 (one ofsaid bearing portions being shown in Fig. 1) and said pin is fixedwithin a projectin lug 10 on the underside of member 6. utward movementof armature member 3 is limited by engagement of a projection 11 onmember 3 with a fixed stop 12 provided on the underside of the lug 10.

Winding 1 is ,mounted on the upper leg of I the U-shaped core member 5and the outer vface of said leg is provided with a pair of paralleltransverse recesses 13 for receiving a shading coil 14. As shown in Fig.3 shading coil 14 comprises a piece of stranded wire formed to provide aloop and having its ends twisted together and fused at 15 by welding,

soldering or the like.

Shading coil 14 is placed in the recesses 13 and is held therein bybending portions of the laminations of core member 5 over the same, asshown at points 16 in Fig. 2, and the twisted portion of said coil isarranged tobe held against the side of said core member by the interiorof winding 1. v

In practice it has been found that a shading' coil arranged andconstructed as above describedV is ca able of withstanding severe shockswithout reaking. This advantage is largely due to flexibility of thecoil and also to prevention of strains on its fused portion 15 by the-twisted portion. The unfused part of the twist provides means to bracerelatively the portions of the stranded wire adjacent the fusedconnection to damp such portions against vibration relative to theconnection and thus protect the coil against breakage at or adjacent theconnection by vibration. While the aforedescribed coil is mounted on thefield member of the electro-4 #comprising field and armature members and2V I 'imacat a shadin coil for one of; said members `formed o strandedwire, having'fused cono nection lof its strands to provide a closed loopand having means to braceprelatively the porl 5 tions' of the strandedwire adjacent the fused connection to protect said ooit against break lage' at or adjacent the fused connection due to *Vibrations 3. An'alternating current electromagnet w comprising field and armaturemembers and a shading coil carried by one of said members, said coilbeing formed of stranded Wire having its end portions twisted togetherand Connected by fusion at a substantial distance l5 from the inner endof the twist.

' liniwitness whereof, Ihave hereunto subscribed'xny name,

' HRAOE N., PACKARD.

